Conventional technologies in this field are those described in the following.
(1) Fluorescence Detection Method
This fluorescence detection method is to immobilize a single-stranded DNA with known nucleotide sequence (probe DNA) on a glass substrate, silicon, diamond, or the like and to detect the hybridization (a phenomenon in which mutually complementary single-stranded DNAs are coupled to form a double-stranded DNA) with unknown single-stranded DNA (target DNA) by a fluorescent substance immobilized on the target DNA. A problem lies here, however, in large scale apparatus necessary to detect the hybridization by means of fluorescence in this method. Furthermore, a limitation is also present in realization in high density because the observation means is a fluorescence microscope.
(2) Electric Charge Detection Method
This electric charge detection method is based on a silicon ISFET (Ion Sensitive Field Effect Transistor). The sensitivity of the silicon ISFET is, however, too low to detect the doubling of the charge due to the hybridization of DNA.
(3) High Performance p-Channel Field Effect Transistor with enhanced threshold voltage resulting from ozone treatment, as Suggested by Present Inventors
This transistor is a p-channel field effect transistor having an electrolyte solution gate and having as a channel a diamond surface which is a mixture of a hydrogen terminated surface and an oxygen terminated surface produced by oxidization of the hydrogen terminated surface by an ozone treatment (see patent document 1 below).
[Patent document 1]
Japanese Unexamined Patent Publication No. 2004-109020